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Taenia infestations: A concise overview
- 1. Taenia infestations Dr Menal Wali Final Yr MD PGT Tropical Medicine
- 2. Helminths • Parasitic worms • Multicellular, • B/l symmetrical, • elongated, flat or round animals
- 3. Phylum 1)NEMATODES - Cylindrical worms- Eg: ascaris, ancylostoma, trichuris, strongyloides, enterobius, filariasis, dracunculus. 2) Platyhelminthes-Flat worms. a)Leaf-like TREMATODES or Flukes. Eg.Blood flukes(schistosomiasis), fasciola, clonorchis, paragonimus,. b)Tape-like CESTODES or Tape worms. Eg.Taenia,echinococcus,diphyllobothrium…
- 4. Cestodes • Flattened, ribbon-like, without body cavity. • Head, neck and segmented strobilus. • Head : suckers, rostellum and hooklets . • Neck : budding zone from which segments are formed. • Strobilus : immature, mature and gravid proglottids. • Hermaphrodites • Digestive tract : absent, nutrition is absorbed by villi of body surface.
- 5. • Complex two-host life cycle • Human beings are the only definitive host • Intermediate hosts can be pigs, cattle and also human being • Most common in Latin America, Africa and India
- 6. Taenia saginata • Also called beef tapeworm • Word wide, highest prevalence (up to 27%) are in central Asia, the Near East, and Central and East Africa. • Habitat: upper jejunum of man • Definitive host : human • Intermediate host : cattle's
- 7. T. saginata
- 8. Morphology • Adult : scolex, neck and strobila • Length : 2-5m but can reach upto 10m • Scolex : large, quadrate, four suckers without rostellum and hooklets • Neck : active structure from which proglottids are continuously formed • Body(strobila) : chain of proglottdis
- 9. • Proglottids : each 20x5mm in breadth and length, • 1000-2000 in numbers • Motile • Expelled singly • No. of lateral branches of uterus 15-30 • Also contains vagina, testes ovary
- 10. Scolex T. saginata T. solium
- 11. Proglottid T. saginata T. solium
- 12. Eggs • Spherical, brown in colour • 31-43µm in diameter • Surrounded by embryophore • Inside the emryophore is the hexacanth embryo(oncosphere) with three pairs of hooklets • Does not float on saturated salt solution • Infective only to cattles
- 13. Egg of T. saginata and T. solium
- 14. Life cycle
- 15. Pathogenesis • Adult tapeworms : minimal local pathology • Vague abdominal discomfort, indigestion, diarrhoea, constipation, loss of appetite • An immune response to adult tapeworms provokes eosinophilia and immunoglobulin E(IgE) elevation in some patients
- 16. Diagnosis • Detection of egg and proglottid in stool • Direct stool smear or by sedimentation technique • Egg do not float on saturated salt solution • Anal swab is superior method • Eggs of T. saginata and T. soluim are very similar
- 17. • Proglottids morphlogy and structure are used to differentiate between the two type of taenia • Scolex structure can also be used
- 18. Treatment • Single dose of praziquentel 10mg/kg is highly effective • Niclosamide single 2gm single dose is also effective
- 19. Prophylaxis • Inspection of all beef for cysticerci bovis • Thorough cooking • Proper disposal of faeces • Infected people should be treated to break parasitic life cycle
- 20. Taenia solium • Also called pork tapeworm • T. solium infection is endemic include Mexico, Central America, South America, Africa, Southeast Asia, India, the Philippines, and southern Europe. • definitive host : human • Intermediate host : pigs or human
- 21. Morphology • Adult : scolex, neck and strobila • Length : 2-4m • Scolex : small, globular, four suckers with rostellum and a double row of hooklets • Neck : active structure from which proglottids are continuously formed • Body(strobila) : chain of proglottdis
- 22. • Proglottids : each 12x6 mm • 800-1000 in numbers • Non motile • Expelled in small chains of 5 or 6 • No. of lateral branches of uterus 5-10 • Also contains vagina, testes ovary • Eggs are similar to that of T. saginata and it can also infect human causing cystercosis
- 23. Life cycle
- 24. Pathogenesis • Similar to that of T. saginata • But humans can also get infected by the egg through autoinfection • Autoinfection occurs by oro fecal route due to poor hygiene and also by reverse peristalsis • Infection by egg leads to cysticercocis
- 25. • Diagnosis of intestinal infection with T. solium is similar to that of T. saginata with egg in stool and species differentiation with proglotid and scolex • All cases of diagnose intetinal T. solium should be examined for cysticercosis
- 26. Treatment • Praziquentel 10mg/kg single dose is the drug of choice • Niclosamide single 2gm single • Vomiting should be avoided to prevent cysticercosis • Puragtives may be given 1-2 hr after antihelminthic treatment • Instructed for carefull washing of both hands after defecation
- 27. Prophylaxis • Personal hygiene • Sanitory measures • Strict inspectuion of pork in slaughter huose • Thorough cooking • Proper disposal of human faeces • Avoid eating raw vegetables grown on soil irrigated by sewage water • Treatment of infected person
- 28. Cysticercosis • Cysticercosis is a disease caused by the presence of cysticercus cellulosae and cysticercus racemose, the larval forms of T. solium in dfferent tissues • A major cause of adult-onset epilepsy in the developing world.
- 29. Target tissue • Predilection for migration to eyes, CNS and striated muscles. • CNS involvement is termed as Neurocysticercosis
- 30. Types of cysts Cysticercus cellulosae • Larva form of T. solium in host tissue • Small (<2cm), round, thin walled • Lodges in the parenchyma or the subarachnoid space • Provokes only a minor inflammation • Often remain silent
- 32. Cysticercus racemose • Large lobulated cysts with predilection for basal cisterns • Causes cysticercotic arachnoiditis and presents as meningitis • Causes obstruction of 4th ventricle and resultant raised ICP and hydrocephalus • Can cause occlusion of vessels and vasculits resulting in stroke • Causes intense inflammatory reaction and seizures
- 33. Prevalance
- 34. Mode of infection • Humans are both intermediate and definitive hosts. • Cysticercosis develops when humans become intermediate hosts by ingesting the embryonated eggs of the tapeworm, which release oncospheres that penetrate the intestinal wall, enter the bloodstream, and disseminate into the tissue.
- 35. • HETEROINOCULATION – eggs may come from the environment • INTERNAL AUTOINOCULATION – regurgitated from proglottids into the stomach • EXTERNAL AUTOINOCULATION – from the fingers of an infected person
- 36. Neurocysticercosis Classification • Anatomical classification • Sotelo et al classification • Carpio et al classification • Chorobski Classification
- 37. Anatomical Classification • Parenchymal NC • Intraventricular NC • Meningeal NC • Spinal NC • Ocular NC
- 38. Presentation • The clinical presentation of NC is determined by • Location of cysts • Size of cysts • Cyst load (number of cysts) • Host’s immune response
- 39. • Parenchymal NC –Seizures –Headache, nausea and vomiting –Stroke –Frontal lobe involvement –Cerebellar Ataxia –Fulminant encephalitis in massive initial infection
- 40. CT image
- 41. • Intraventricular NC – 5- 10% of all cases – 4th ventricle most common site for obstruction – Cysts in lateral ventricles less likely to cause obstruction – Hydrocephalus and acute, subacute or intermittent signs of raised ICP without localizing signs
- 43. • Meningeal NC – Meningeal irritation resembling TBM – Raised ICP from oedema, inflammation and presence of cyst obstructing flow of CSF
- 44. • Spinal NC – Spinal cord compression – Nerve root pain – Transverse myelitis – Arachnoiditis • Ocular NC – Visual impairment (decreased visual acquity) – Scotoma, retinal detachment, iridocyclitis
- 45. Investigations • Stool Routine and Microscopy • Fundoscopy • Biopsy and histopathology • CT with contrast • MRI • Serology – EITB • sensitivity of 98% specificity of 100% – ELISA in CSF • sensitivity of 87% specificity of 95
- 46. Diagnostic Criteria for Human Cysticercosisa • 1. Absolute criteria a. Demonstration of cysticerci by histologic or microscopic examination of biopsy material b. Visualization of the parasite in the eye by funduscopy c. Neuroradiologic demonstration of cystic lesions containing a characteristic scolex • 2. Major criteria a. Neuroradiologic lesions suggestive of neurocysticercosis b. Demonstration of antibodies to cysticerci in serum by enzyme-linked immunoelectrotransfer blot c. Resolution of intracranial cystic lesions spontaneously or after therapy with albendazole or praziquantel alone • 3. Minor criteria a. Lesions compatible with neurocysticercosis detected by neuroimaging studies b. Clinical manifestations suggestive of neurocysticercosis c. Demonstration of antibodies to cysticerci or cysticercal antigen in cerebrospinal fluid by ELISA d. Evidence of cysticercosis outside the central nervous system (e.g., cigar-shaped soft- tissue calcifications) • 4. Epidemiologic criteria a. Residence in a cysticercosis-endemic area b. Frequent travel to a cysticercosis-endemic area c. Household contact with an individual infected with Taenia solium
- 47. Diagnosis • Definitive a. 1 absolute b. 2 major + 1 minor + 1 epidemiological • Probable a. 1 major + 2 minor b. 1 major + 1 minor + 1 epidemiological c. 3 minor + 1 epidemiological
- 48. Tuberculoma Versus Cysticercus Granuloma Cysticercus Granuloma • Round in shape • Cystic • 20mm or less with ring enhancement or visible scolex • Cerebral edema not enough to produce midline shift or focal neurological deficit Tuberculoma • Irregular in shape • Solid • Greater than 20mm • Associated with severe perifocal edema and focal neurological deficit
- 49. Natural course • Rate of spontaneous resolution of a solitary cysticercus granuloma in patients with seizures • 3 months - 18.8% • 6 months - 36.4% • 1 year - 62.5%
- 50. Treatment • Antiepileptic therapy • corticosteroids (dexamethasone) • albendazole (15 mg/kg per day for 8–28 days) or praziquantel (50–100 mg/kg daily in three divided doses for 15–30 days).
- 51. Steroids • Corticosteroids represent the primary form of therapy for cysticercal encephalitis and arachnoiditis causing hydrocephalus and progressive entrapment of cranial nerves. • High doses of iv Dexamethasone can be followed by oral therapy with Prednisolone 1mg/kg/day or Dexamethasone 0.1mg/kg/day administered 3 times a week
- 52. • glucocorticoids induce first-pass metabolism of praziquantel and may decrease its antiparasitic effect • cimetidine should be co-administered to inhibit praziquantel metabolism • For this reason albendazole is preferred
- 53. Surgery restricted to • Placement of ventriculo-peritoneal shunts for hydrocephalus • Excision of single big cysts causing mass effect • Endoscopical excision of intraventricular parasites.
- 54. Recommendation • Individualize therapeutic decisions, including whether to use antiparasitic drugs, based on the number, location, and viability of the parasites within the nervous system; • Actively manage growing cysticerci either with antiparasitic drugs or surgical excision;
- 55. • Prioritize the management of intracranial hypertension secondary to neurocysticercosis before considering any other form of therapy; and • Manage seizures as done for seizures due to other causes of secondary seizures (remote symptomatic seizures) because they are due to an organic focus that has been present for a long time
- 56. • Treatment with albendazole plus antiepileptic drugs has no benefit over treatment with antiepileptic drugs alone. • Albendazole treatment may cause problems or have adverse effects with regard to increased seizure frequency, encephalopathy and hospital readmissions in the early part of the treatment. • Albendazole treatment may be disadvantageous from an economical perspective because of the direct and indirect treatment costs and the loss of working days
- 57. Uncummon taenia • Taenia saginata asiatica : closely related to T. saginata with pig as intermediate host • Taenia crassiceps cysticercosis : Rodents are the preferred host but rare human infections have been reported, most recently in association with AIDS. • Taenia multiceps is a parasite of dogs, with sheep being the principal intermediate host. Larva is called coenurus.
- 58. Thank you